cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A168644 Triangle read by rows: T(n, k) = [x^k] p(x,n), where p(x,0) = 1, p(x,n) = (7 - n)*(1+x)^n - (6-n)*(1 + x^n) for 1 <= n <= 5, and p(x,n) = 5*(1 + x)^n - Sum_{i=0..3} (Sum_{j=0..i} binomial(n, j)*(x^j + x^(n-j))) + (1/6)*n*(n - 1)*(n - 5)*x^(n-3) for n >= 6.

Table of values

n a(n)
0 1
1 1
2 1
3 1
4 10
5 1
6 1
7 12
8 12
9 1
10 1
11 12
12 18
13 12
14 1
15 1
16 10
17 20
18 20
19 10
20 1
21 1
22 12
23 45
24 65
25 45
26 12
27 1
28 1
29 14
30 63
31 140
32 154
33 63
34 14
35 1
36 1
37 16
38 84
39 224
40 350
41 252
42 84
43 16
44 1
45 1
46 18
47 108
48 336
49 630
50 630
51 384
52 108
53 18
54 1
55 1
56 20
57 135
58 480
59 1050
60 1260
61 1050
62 555
63 135
64 20
65 1

List of values

[1, 1, 1, 1, 10, 1, 1, 12, 12, 1, 1, 12, 18, 12, 1, 1, 10, 20, 20, 10, 1, 1, 12, 45, 65, 45, 12, 1, 1, 14, 63, 140, 154, 63, 14, 1, 1, 16, 84, 224, 350, 252, 84, 16, 1, 1, 18, 108, 336, 630, 630, 384, 108, 18, 1, 1, 20, 135, 480, 1050, 1260, 1050, 555, 135, 20, 1]